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1. Field of the Invention
The present invention relates to computers and particularly to methods and apparatus for idle detection and power saving in computers.
2. Description of the Related Art
The need for idle-detection arises when, for example, a computer or part thereof is to be slowed down or stopped in order to conserve power. The need to save power is particularly important in battery-operated computers in order to extend battery life. Portable computers are typically battery-operated and hence the need to save power is becoming increasingly important as the use of portable computers increases.
Power consumption is distributed among the major parts of a computer. One part of the computer with significant power consumption is the CPU. Other parts include each of the input/output (I/O) devices such as display screens, keyboards, modems, printers, disk drives and the like. Still another part with significant power consumption is memory.
Prior art attempts at conserving power have generally focused on a single part of the computer such as a particular one of the I/O devices.
For example, to save power for the screen display, systems have detected screen inactivity and employed screen blanking for an idle screen to reduce the power to the display screen when the screen has not been used for some period of time. Typically, a timeout circuit senses changes in screen information and, if no change has occurred for a predetermined timeout period, the backlight to the screen is turned off for power reduction. While screen blanking is effective in reducing power for the display screen, no reduction results in power to the driver circuitry for the display, to the CPU, or to other parts of the computer.
Other prior art attempts at conserving power consumption have focused on disk drives because the power consumption of rotating magnetic disks is high. Disk drive manufacturers have employed various schemes for reducing the power consumption of the disk drive. While such power consumption schemes are effective for the disk drive, no reduction results in power to the CPU or other parts of the computer.
Other attempts at conserving power have done so only when relatively long periods of idleness exist.
In order to reduce power consumption in computers, there is a need for improved idle detection methods and apparatus.